The present invention generally relates to centrifuges and more specifically to a spring operated swing out rotor system for a centrifuge.
Traditionally, there have been two types of centrifuge rotors, “angled rotors” and “swing out rotors”. The rotor is the part of the centrifuge that spins during centrifugation and holds the vessel. Angled rotors hold the tube/vessel at an angle, usually somewhere in the area of 45°. This is the easier type of rotor to manufacture and therefore is usually less expensive. Swing out rotors are designed so that the tube or vessel is inserted vertically or sufficiently tilted so that the tubes will not spill, and during centrifugation, the rotor carrier (also called buckets, shields or inserts) “swings out” so that when spinning, the tube is held horizontally. The advantage to spinning the vessel horizontally is that the separation occurs in a way that produces the supernatant to be collected perfectly at the very bottom of the tube.
Swing out rotors often consist of a rotor and carrier. The conventional rotor has two retaining elements for each carrier. When at rest, the carrier is horizontal and holds the vessels vertical due to gravity alone, so that the sample tube or vessel does not require a cap or lid. During centrifugation, the centrifugal force swings the carrier so the vessels are in a horizontal position. When centrifugation is complete, the tubes revert to their original position due to gravity.
In an ordinary swing-out centrifuge, gravity alone holds the vessels vertical or sufficiently tilted before use, and then the centrifugal force rotates the vessels into a nearly-horizontal position. Before use, gravity delicately urges the default position of the carrier tray to be in a position to avoid spillage, but there is little or nothing else to maintain that orientation, so that the entire tray of vessels may rotate out of position and spill liquid if the system is bumped. During use, gravity opposes the centrifugal force, and therefore the tube might “droop” and not be perfectly horizontal. The rotor may have difficulty sustaining the vessels in a completely horizontal orientation.
It would be desirable to have a rotor where the carrier tray is sufficiently tilted before use so that the vessels will not spill, but the system benefits from the centrifugal forces to urge the vessels into a horizontal position when spinning.